Many devices use steam to treat garments and other objects to remove wrinkles, for cleaning or for other purposes. For example, a steam iron discharges steam from a soleplate onto a fabric of a garment to help remove wrinkles. In another embodiment, a steam cleaner may comprise a hose with a steam applicator that a user moves to direct steam onto fabrics, such as curtains or upholstery. Typically these devices comprise a boiler that heats and evaporates water to produce the required steam, which is conveyed to some means of applying the steam to an article. Scale forms when water is evaporated to produce steam and impurities and other substances which were dissolved in the water are left behind and form solid compounds. This is particularly common in areas where the mains water supply is hard water, i.e. it contains a relatively high level of impurities such as calcium and magnesium.
Furthermore, if a boiler is not regularly rinsed and cleaned then the water that remains in the boiler can become contaminated. This is a result of the scale and other impurities which remain in the boiler as solids or dissolved in unevaporated water. Therefore, over time, water in a boiler will become progressively more contaminated with impurities, and a foam substance may be produced.
The impurities and foam may be carried by the contaminated steam and may mark, stain and possibly damage any garment or other article which is being treated, as well as cause blockages in other parts of the device.
WO2008/075308A2 discloses a steam generator with a filter at the outlet of the boiler that removes impurities from steam. However, the end of the filter may become blocked by impurities and foam, which will reduce the possible steam flow rate through the filter.